Cherokee Vibration

ChrisMc

ChrisMc

Well-Known Member
Joined
Aug 11, 2009
Location
Holly Springs, NC
1999 Cherokee
4.0L 5 speed
6.5" Long arm lift
SYE
Custom rear drive shaft
Stock front driveshaft but was balanced
Locked LP D30
Open 8.8 (Pinion angle should be correct)

I get a vibration (more of a loud hum that you can feel) only at 55-60 and doesnt matter what gear its in. Planned on replacing the front with a HP30 for driveline angle sake, just got a steal on the LP30. If I remember correctly, it still happens when the front DS is out though.

General solutions: Driveline angles, t-case rebuild, u-joints.

Am I missing anything else, or does anyone have any other ideas before I start?
 
55-60 on the uncorrected speedometer?

Add wheel bearings to the list. Try see maybe if you can pick it up on a audio spectrum analyzer.. also double Cardan joints can get loose at the centering ball...
 
Good way to rule out spider gears in rear axle is to throw trans in N around curves if vibration goes away it's def spider gears... sounds like rear diff of some sort I just drained my 14bolt yesterday and oil was black as devils soul!!
 
ChrisMc said:
55-60 actual speed, I do have the correct speedo gear in it.
Click to expand...
Yeah but does it account for your tire size? IfI look close at the driveshaft and Universal's first. Put in neutral, brake or block wheels and check slack. Go from there. Probably wouldn't hurt to service the diff fluid & inspect while you have the cover off.
 
I got $20 on rear driveshaft and/or pinion angle.
Since it's a 99 with a SYE. Swap the front shaft to the rear and re-evaluate.
I ran into a similar issue last year and that was how I singled out the rear shaft.
A vibe at a small window like that is almost always going to be driveline related.
Is the rear pinion a couple degrees lower than the rear output?
Is the centering ball nice and tight?
 
Does it vibrate at that speed even if you let off the throttle? If it stops, it’s in the drive line.
I once had an XJ that kept eating rear u joints. I changed yokes, shim packs, and changed the drive shaft. Still kept eating them up. It wound up being the T case bushing was shot letting the T case lift and move to the side under throttle. I felt like an idiot but I was young and dumb back then. Now I’m older but still dumb.
 
Huh. I wonder if that's why my xj ate the two cups on the slip yoke side of the joint? Advance said they had some mismachined joints with missing grease passages at one time.
 
I had one where the Advance Adapters SYE yoke was touching the grease fitting on the CV portion of the driveshaft.
But in that case, the chatter came in at about 15 MPH. I was able to spot a witness mark on the yoke and then clearanced it to stop the noise/vibe.
 
Jody Treadway said:
I got $20 on rear driveshaft and/or pinion angle.
Since it's a 99 with a SYE. Swap the front shaft to the rear and re-evaluate.
I ran into a similar issue last year and that was how I singled out the rear shaft.
A vibe at a small window like that is almost always going to be driveline related.
Is the rear pinion a couple degrees lower than the rear output?
Is the centering ball nice and tight?
Click to expand...

This.
I had this same issue. I ended up having to cut the drive shaft and re weld it myself with a dial indicator on it. Got it with in .008 and problem solved.
 
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